Therapeutic apparatus



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THERAPEUTIC APPARATUS Filed June 18, 1945 2 Sheets-Sheet. 2

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Inventor William H. flearsle y,

His Attorney Patented Jan. 13, 1948 THERAPEUTIC APPARATUS William K.Kearsley, Schenectady, N. Y., assignor to General Electric Company, acorporation of New York Application June 18, 1945, Serial No. 600,168

Claims. (CL 128-421) The present invention relates to the production ofelectric currents for therapy purposes, and in general to the productionof currents of controlled frequency and amplitude. The objects of myinvention are to provide an apparatus for producing alternating currentsover a wide range of frequency and which are adapted to the needs ofpatients being treated.

It is desirable that the frequency of electric currents which areemployed for the treatment of patients should be smoothly regulated,that is, the frequency should be capable of being varied in a continuousor stepless manner as contrasted with step-by-step or intermittentchange from one frequency to another. A therapist having at his disposala source of alternating (sinusoidal) currents, the frequency of which isreadily controllable by stepless gradations, is in a position to readilyarrive at the frequency having the most favorable therapeutic effect.For example, when it is desired to produce muscular response in the caseof injured nerves to prevent atrophy of muscles of a patient, it isfound that the greatest response with minimum current value is obtainedat a critical range of frequency which is likely to be different fordifierent patients. An apparatus permitting rapid determination ofoptimum frequency insures that the discomfort to the patients due to theheating effect of the current at the areas of application will bereduced to a minimum.

It is one of the objects of my present invention to provide means forobtaining sinusoidal currents of a wide range of smoothly controllablefrequency. Such currents are sometimes referred to as carrier currentsby the therapists.

It is another object of my invention to provide means for continuouslymodulating the carrier currents at chosen modulating frequencies bystepless gradations.

As will be described in greater detail in connection with theaccompanying drawings, apparatus embodying my invention includesphototubes and means for subdividing and varying light received by thephototubes into pulses. With properly correlated amplifying means,therapy I currents are produced in response to such light pulses and bythe means provided in this new apparatus the characteristics of therapycurrents best adapted for the treatment of patients may be quickly and'emciently regulated.

In the drawings, Fig. 1 is a somewhat conventionalized perspective viewof apparatus provided with hand-controlled regulators for varying andregulating therapy currents over a wide range of characteristics; Fig. 2is a diagram of an electrical converting system: and Fig. 3 is a graphillustrating modulated carrier currents produced by the apparatus.

Referring to Fig. 1, the drawing shows two photocells I, 2, arranged toreceive light from a source 3 through a window 4 in an opaque housingwhich has been shown broken away except for a wall part 5 surroundingthe window. In the path of the beam of light passing from the source 3to the photocells is located an opaque rotatable mask or screen 6 whichis provided with a plurality of radially arranged apertures 1,constituting light-transmitting windows whereby the light beam issubdivided into pulses which activate the respective photocells.

The amount of light transmitted to the photocells also may be modulatedby a shutter 8 which, as will be described hereinafter, is caused topass in a controlled manner between the source of light and thephotocells.

The screen 6 is mounted for rotation on a shaft 9 which is connected bya train of gears (later described) to an electric motor Ill. The geartrain includes conventional toothed gears H, I!

and a plurality of adjustable frictional gear disks l3, l4, and I5.Cooperating with the gear disks are small rubber-tired wheels l6 and I!which arearranged to be moved by a shaft l8 between the centers and theperipheries of the disks l3, l4, and I5, the supports for the shaft I8being only conventionally indicated at I 9, 19 to simplify the drawing.The shaft I8 is screw-threaded into a U-shaped cradle 20, the purpose ofwhich i is to adjust the position of the wheels l6, IT.

The cradle 20 slides in a trough 2i. The position of the disk and ringmembers with respect to one another is indicated on a scale 23 by apointer 24 which is attached to thecradle 2B.

The disk [3 is mounted on the shaft 25 which is driven by the motor I 0and is urged by the sprin 26 on the shaft 25 into frictional engagementwith the rubber-tired wheel IS. The latter is rotatably mounted on thehorizontal support 2'! which does not rotate. The rubber-tired wheel 16in turn drives the disk H which is mounted on the shaft it. The bearingfor the shaft M has not been shown in order to simplify the drawing. Thedisk II in turn engages the rubber-tired wheel I! which frictionallyengages tlzie disk i5 against which it is urged by the spring 2 Byturning the adjusting knob 3|, the regions of engagement of therubber-tired wheels l6 and I 1 may be adjusted on the disks l3, l4, andI5;

that is, the frictional engagement of the wheels I8 and Il may be causedto occur at various distances from the center of the disks outwardly tothe periphery, thereby varying the relative speeds of the drivenmembers. The highest speed is obtained when the wheel I6 bears adjacentthe outer periphery of the disk I3 and also near the center of the diskI4, the wheel I1 then engaging near the periphery of the disk I4 andnear the center or the disk I5. Conversely, lower speeds can be obtainedwhen the wheel I8 engages near the center of the rotation of the disk I3and the periphery of the disk I4, the wheel I'I then engaging at aregion near the center of the disk I4 and with the periphery of the diskI5. By the resulting wide variation of speeds, the rotation of theapertured disk 6 may be varied several thousandfoid. By this means theoperator may cause subdivision of the light beams falling alternatelyupon the photoelectric cells into shorter or longer pulses.

As will be later explained, the currents generated by the light pulsesfalling alternately upon the photoelectric cells are caused, byappropriate electronic relays, to result in carrier current of chosenmilliamperage and voltage which are suitable for use in the therapyfield, and the frequency of such currents may be smoothly varied over awide range. For example, by this means the carrier frequency of theoutput currents may be varied readily from one per minute to 120 persecond, although wider variations are possible.

In some cases it is desirable in the therapy treatment of patients tomodulate the carrier frequency to produce a train of carrier wavesrising from zero to a maximum, and then falling to zero, as indicated inFig. 3. Such modulation of the carrier currents is carried out by theshu ter 8 which is caused to be oscillated to cover and uncover thewindow 4 at a predetermined rate.

The shutter 8 is given an oscillating motion by a shaft 32 which ismounted between bearings as indicated in the drawing, the supports nothaving been shown. The shaft 32 is connected by levers 33 and 34 to a.rotating disk 35. The pin 36 on the disk 35 en ages with the end of thelever 34 to cause the motion of rotation of the disk 35 to be convertedinto oscillating motion, thereby modulating the light falling on thephotocells as will be evident from the drawing.

The disk 35 is rotated by the disk 31 which is I mounted on the commonshaft 38. A spring 39 presses the disk 31 against a rubber-tired wheel40 which in turn engagesdvith and rotates a disk 4|, The latter engageswith a rubber-tired wheel 42 which in turn engages with a disk 43 in amanner already described in connection with the main driving mechanismfor the apertured disk 6. The disk 43 is mounted upon a shaft 44 drivenby a slow speed electric motor 45. The mountings and engagement of thedriving and driven members are similar to those of the first-describedadjustable gear train. The position of the shaft 46 is similarlyadjusted by a thumb-screw 41 to indicate on a scale 48 the relativeposition of the gears and hence the rate of modulation.

The oscillating shutter is shown as an example of a light modulator, butmy invention is not to be considered as limited to this particular formof modulator.

The wave form of the therapy currents delivered to the applicatorterminals 61 and I5 (Fig. 2) is determined by the rate of change orcrosssectional area of the light pulses falling on the photocells. Thelight variations are in turn determined by the configuration or thewindows in the screen 8 and the configuration of the shutter 8. Thephotocells I and 2 should be so positioned with respect to the source oflight and the spacing of the windows in the screen 6 that a desiredeffeet is obtained. The operation may be made more evident if it isassumed that the screen 6 has but a single window. The beam of lightshining through this window would sweep across photocell I, producing inan amplifying system hereinafter described one-half Of the carrierfrequency wave. It would next sweep across the photocell 2 therebyproducing the opposite half of the carrier frequency wave. By providinga plurality of windows this operation is repeated rapidly and results ina continuous train of waves.

By modulating the pulses, as by shutter 8, the amplitude of the carrierfrequency waves may be varied, as shown in Fig. 3. By suitably choosingthe shape of the windows in the screen 6, and the shape of the shutterwith respect to the configuration of the active cathode surface of thephotocells, variations in the wave form of the therapeutic currents areproduced.

The variable currents in the phototube circuits resulting from thevariable pulses of light falling on the photocells is amplified by relaytubes to produce desired therapy currents. A system of connections forthis purpose is shown in Fig. 2. Referring to this figure, a photocell,conventionally indicated at I, has its anode 50 and its cathode 5|connected to spaced points of a variable resistor 52 by the conductors53, 54.' A variable resistor 55 is provided in circuit with the cell.The terminals-of the resistor 52 are connected by the conductors 56, 51to the extremities of the series-connected capacitors 58, 59. Thecapacitor 58, which is of relatively large capacity (e. g. 32microfarads) is charged by the full wave rectifier 60. The capacitor 58,having a smaller capacity, is maintained charged by a half-waverectifier iii. The anodes 62, 62 of the rectifier are connected by theconductors 83, 64 to the respective terminals of the secondary windingof a transformer 85. The thermionic cathode 88 of the rectifier 60 isconnected by a conductor 56 to one terminal of the resistor 52 and fromthence to the applicator terminal 51 of the therapy outfit, a choke 68being included between the cathode 66 and the capacitor 58.

The output circuit conductors 69, III of the phototube are connectedrespectively to the anode and the grid of a pliotron (vacuum) tube IIand by the conductors I2 in series with a resistor I3 to thepotentiometer 52. The cathode of the pliotron II is connected to thegrid of a second pliotron 14. The anode of the pliotron I4 is connectedto the opposite applicator terminal I5 of the therapy apparatus. Thecathode of the pliotron 14 is connected by the conductor 16 to a pointof intermediate potential on the secondary of the transformer 65. Thehalf-wave rectifier BI is connected to the secondary of transformer 65by the conductor 11. A filter capacitor I8 and a choke 19 are providedin the charging circuit of the capacitor 59.

The pulses of light falling on the photocell I cause variations in theresistivity of the photocell which produce variations of the potentialof the grid of the pliotron 1 I. The resulting change in the current inthe circuit I2 varies the potential of the cathode of the pliotron IIand in turn varies the potential of the grid of the pliotron I4.Consequently the output currents derived from the capacitor 58 andtransmitted by the pliotron 14 are varied in accordance with thevariations of the light pulses, The characteristics of the transformersecondary and the described circuits are chosen to obtain therapycurrents of desired characteristics.

The described circuit elements constitute onehalf of the system andalone will produce variable unidirectional currents. By the duplicatingof the described circuits, as indicated in the lower part of Fig. 2,unidirectional carrier currents of opposite polarity are impressed onthe applicator terminals 61, 15. The corresponding parts of the lowerhalf of Fig. 2, which contains the photocell 2, are identified by thesame numerals as the upper part with the addition of a prime sign.

The grids of the pliotrons l4 and 14' are normally biased at a negativecutofl potential by the capacitors 59 and 59'. As previously explained,only when light activates the phototubes is the cutoff potentialmodified to permit current flow. As the light shines on only onephotocell at any instant the potentials of the tubes 14, 14' arealternately modified, which results in the production of alternatingpotentials at the applicator terminals 61, I5. I

For some purposes, non-pulsating direct current is desired fortherapeutic purposes. Unidirectional current may be obtained fromapplicator terminals 80, 8| which are connected to a variablepotentiometer 82. The latter is connected by the conductors 83, 84 tothe terminals of the capacitor 58 in circuit with a switch 85.

What I claim as new and desire to secure by Letters Patent of the UnitedStates. is:

1. An electrotherapeutic apparatus comprising the combination ofapplicator terminals, a source of unidirectional electric energy,thermionic means for transmitting said energy to said terminals,photoelectric means operatively related to said thermionic means wherebythe currents delivered by said thermionic means may be controlled, meansfor activating said photoelectric means with light pulses and means forvarying steplessly the frequency of said light pulses whereby thefrequency of therapeutic currents delivered to said terminals may becorrespondingly varied.

2. A therapy apparatus for furnishing electric currents at a desiredtherapeutic characteristic which comprises the combination of a sourceof unidirectional current, thermionic tubes for transmitting saidenergy, photoelectric means connected to control the operations of saidthermionic tubes, a source of light positioned to transmi t a beam oflight to said photoelectric means, a rotatable opaque disk having aplurality of lighttransmitting windows located in the path of said lightbeam whereby said beam may be subdivided, means for rotating said disk,means for steplessly and uninterruptedly varying the rate of rotation ofsaid disk in order to vary the frequency of light subdivision, and meansfor independently modulating said light beam.

3. An apparatus for transmitting an electric current at a desiredfrequency and amplitude which comprises the combination of aphotoelectric cell, a source of light positioned to transmit light tosaid cell, a rotatable mask having a plurality of light-transmittingwindows located in the path of light between said source to said cellwhereby the transmitted light may be subdivided,

means for rotating said mask, means for uninterruptedly and steplesslyvarying the rate of rotation of said mask, an energy source, athermionic device connected to transmit currents from said source inresponse to the currents transmitted by said cell, and applicatorterminals circuit connected to said thermionic device.

4. A therapy apparatus for furnishing electric currents of desiredtherapeutic characteristics which comprises the combination ofapplicator terminals, a plurality of sources of unidirectional electriccurrent, transmitting circuits each containing pliotron vacuum tubesconnected between said sources and said terminals, photoelectric meansconnected to said tubes to control the transmission of current thereby,a light source whereby a beam of light is transmitted to activate saidphotoelectric means, a rotatable screen having windows for subdividingsaid beam, a motor for rotating said screen, mechanical means forsteplessly regulating the rotational speed of said screen, alight-modulating shutter in the path of each of said light beams andmeans for varying the movement of said shutter and thereby modulatingthe currents impressed upon said applicator terminals.

5. An electrotherapeutic apparatus comprising the combination ofapplicator terminals. a source of electric energy, thermionic device fortransmitting energy from said source to said terminals, a photoelectricdevice connected to control said thermionic device, means for deliveringa beam of light to said photoelectric device, means for subdividing saidbeam into pulses of desired amplitude, and mechanical means foruninterruptedly varying the frequency of the resulting light pulses inthe approximate range of one cycle per minute to about cycles persecond, thereby correspondingly varying the frequency of therapeuticcurrents delivered to said terminals.

6. An electrotherapeutic apparatus comprising the combination of asource of electric energy, thermionic means for converting said energyinto therapeutic currents, a photoelectric device connected to controlthe operation of said thermionic means, means for activating saidphotoelectric device with light pulses the duration and frequency ofwhich correspond to the desired characteristic of therapeutic carriercurrents and means for modulating said light pulses at a frequency lowerthan the frequency of said carrier currents.

7. An electric apparatus comprising the combination of output terminals,duplicate energy supply circuits containing pliotron tubes con nected tosaid terminals, means for biasing the grids of said pliotrons at cutoffpotential, a photoelectric cell in each of said circuits respectivelyconnected to initiate the flow of energy through said pliotron tubes,means for alternately illuminating said cells with pulses of light andmeans for steplessly varying the frequency of said pulses withoutinterrupting the operation of said apparatus.

8. An electrical apparatus comprising output terminals, duplicate energysupply circuits each containing a pliotron connected to said terminals,means for biasing the grids of said pliotrons at cutofl potential,aphotoelectric cell in each of said circuits, circuit elements betweenthe cells and pliotrons in said respective circuits to initiate the flowof energy through said pliotrons when said photoelectric cells areilluminated, means for alternately illuminating said cells with pulsesof light, means for steplessly varying the frequency of said pulses andmeans for modulating said pulses.

7 9. An electrical apparatus comprising output terminals, duplicatecircuits containing electric capacitors, means for charging saidcapacitors, pliotron tubes respectively connected between saidcapacitors and said terminals, a photoelectric cell in each of saidcircuits, means for biasing the grids of said pliotrons at cutoflfpotential, electric connections between said cells and the grid circuitsof said pliotrons whereby said grid potentials are modified to permitthe transmission of current from said capacitors to said terminals,illuminating means, a screen having windows for transmitting pulses oflight from said source alternately to said cells, means includingadjustable friction disk gearing for rotating said screen and means formodulating said light pulses.

10. A therapeutic apparatus consisting of the combination of applicatorterminals, paired duplicate circuits containing electric capacitors,transformers respectively associated with each of said capacitors,rectifiers connected to charge said capacitors from the associatedtransformer, a pliotron tube in each of said circuits connected betweenthe capacitor of said circuits and said applicators, means for biasingthe grids of said pliotron tubes at cutoff potentials, a photoelectriccell in each of said circuits, electric connections between said cellsand the associated pliotron tubes in each circuit whereby uponillumination of said cells the grid potential of the respectiveassociation pliotron tubes may be modified to transmit current derivedfrom the associated WILLIAM K. KEARSLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,475,583 Hoxie Nov. 27, 19231,916,356 Bohner July 4, 1933 2,213,820 Maxson Sept. 3, 1940 2,243,591Westendorp May 27, 1941 2,311,935 Dobert Feb. 23, 1943 2,333,760 Babo etal Nov. 9, 1943 FOREIGN PATENTS Number Country Date 108,475 AustraliaSept. 2, 1934

